The invention relates generally to Integrated Circuit (IC) cards or smart cards used in processing transactions involving goods and services. Smart cards are plastic cards having microprocessor and memory circuits attached to the front or back side that connect to electrical contacts located on a front side of the card. The circuits are activated and data accessed from the card by inserting the card into a reader device that makes connections to the electrical contacts. More particularly, the invention relates to a device and method for connecting a smart card having a Universal Serial Bus (USB) interface to smart card reader devices that require no active electronic circuitry. Furthermore, the invention relates to a novel method and device for providing visual indication of data flow activity from the smart card.
Smart cards are a class of data cards. Data cards used in processing transactions are either passive or active in nature. Passive data cards include traditional credit, debit and ATM cards that make use of stored data on a magnetic strip on the back of the card. When a transaction is processed using a passive data card, transaction verification is generally required via a reader device connected to a remote computer over a telephone network. During a transaction, data may be written and read from the magnetic strip. Active data cards or smart cards make use of processor and memory circuits embedded on the card that are activated when the card is connected to a reader device. Since smart cards may contain the intelligence required to complete a transaction, the transaction may be completed locally without resorting to a telephone connection to a remote transaction verification facility. In addition to storing data related to the owner""s account such as identification number and account balance, the circuits also contain encryption for security purposes. Smart cards are used in many applications, including Subscriber Identification Module (SIM) in Global System for Mobile (GSM) telephones, TV satellite receivers, banking, health care programs, parking and highway toll payment, etc. Smart cards are expected to find increasingly wider application, eventually replacing magnetic strip type data cards.
The basic smart card standard is the International Standard ISO 7816, which provides detailed requirements for the physical, electrical, mechanical, and application programming interface for IC cards with contacts. In particular, International Standard ISO 7816-1 Physical Characteristics, International Standard 7816-2 Dimension and Location of the Contacts, International Standard ISO 7816-3 Electronic Signals and Transmission Protocols, and International Standard ISO 7816-10 Electronic Signals and Answer to Reset for Synchronous Cards are incorporated herein by reference. This standard provides for a serial interface connection to the smart card. In a great majority of cases, these cards are used in a reader connected to a computer. The reader for smart cards that comply with the ISO standard contains electronic circuits that enable communication between the card and the computer. The smart card is inserted into a card reader connector that allows a card reader first interface to communicate with the smart card. A second card reader interface is connected to a computer by means of a serial port link, a parallel port link, or a Universal Serial Bus (USB). The smart card reader based on the ISO standard makes use of a micro-controller with its associated software. Electronic components perform the task of translating signals between the smart card and the computer. Some of these components are dedicated to the visualization of the data flow between the application running on the computer and the smart card.
The ISO 7816-3 class B operating conditions make use of the RESET (RST), clock (CLK) and input/output (I/O) communication signals. A smart card reader generates signals RST, CLK and merely buffers the half-duplex communication link on I/O. The signals VCC, GND, RST, CLK and I/O are connected to smart card module contacts. The ISO 7816 smart card reader provides for communication between the computer-based customer application and the smart card by means of an electronic interface circuitry. This interface drives a device that provides a visual indication of I/O activity in the link. Generally, a Light-Emitting Diode (LED) is used for visual indication.
The Universal Serial Bus (USB) has recently become firmly established and has gained wide acceptance in the Personal Computer (PC) marketplace. The USB was developed in response to a need for a standard interface that extends the concept of xe2x80x9cplug and playxe2x80x9d to devices external to a PC, and enables users to install and remove external peripheral devices without having to open the PC case or to remove power from the PC. The USB provides a low-cost, half-duplex serial interface that is easy to use and readily expandable. The USB also supplies up to 500 mA of current at 5 volts to interconnected devices. The USB is currently defined by the Universal Serial Bus Specification written and controlled by USB Implementers Forum, Inc., a non-profit corporation founded by the group of companies that developed the USB Specification. In particular, Chapter 5 USB Data Flow Model, Chapter 7 Electrical, and Chapter 8 Protocol Layer of Universal Serial Bus Specification are incorporated herein by reference. The increasingly widespread use of the USB in computers has led smart card reader manufacturers to develop USB interfaces for connection of their products to computers to complement the existing serial and parallel interfaces. However, because of the differences between the serial interface defined by ISO 7816 and the serial interface defined by the USB specification, smart cards have not been directly compatible with the USB specification. And different card reader configurations have been required due to incompatibility constraints between the various computer interface standards.
The widespread use of the USB in computers has led smart card and smart card reader manufacturers to further develop their products and further reduce costs. A USB smart card reader establishes a communication link between a computer-based application and a smart card or plug module. The USB smart card reader or the USB token reader provide contacts for the interconnections between the USB signals and the four corresponding contact zones of a smart card module fitted out with an IC. The USB smart card reader connects smart card module contacts C1 and C5 as well as pins C4 and C8 respectively to the USB signals VBUS, GND, D+ and Dxe2x88x92. There is no electronic circuitry that enables the activity of the link to be reported. The smart card reader complexity has been transferred into the computer, reducing the overall costs. The USB smart card needs a pass-through connector and a driver to communicate with the computer. This architecture reduces the number of electronic components and consequently the cost without compromising the data transfer speed and the transfer reliability. There is only one IC on a USB smart card to perform communications, computing and storage.
For the foregoing reasons, there is a need to provide a smart card with a USB interface that enables a smart card to connect to an USB port without the need for any interposing electronic circuitry, enabling application software in a computer to communicate through a specific smart card software driver directly with the USB interface on the smart card. There is a further need to provide a visual indication of successful data transfers between a computer and an IC module positioned on a smart card.
The present invention is directed towards a method and device for providing a smart card with the capability of supporting the serial interface defined by the USB specification. It relates to a physical link between a USB port and a smart card. Furthermore, the present invention is also directed towards a method and device for connecting a smart card to a USB port with a simple connector without the need for any interposing electronic circuitry. The invention further relates to a device and method to visualize data flow to and from a smart card.
A communication pipe is established between the client software in a computer and USB smart card endpoints. A USB smart card serial engine captures the downstream traffic and delivers it to a smart card micro-controller. The USB smart card serial engine broadcasts the upstream traffic from the smart card micro-controller to the computer. The upstream and the downstream traffic are composed of packets. Every time a packet transfer occurs without error, the USB smart card serial engine hardware generates a Correct TRansfer (CTR) flag that results in an interrupt. The USB smart card software clears this flag once the interrupt has been serviced. The CTR signal drives a first stage of a ten-bit counter. One output is selected for driving an I/O buffer connected to an I/O connector pin. This pin is connected to an LED on a smart card reader that blinks at a pace set by the USB traffic. All functions are included in a single IC, and the only electronic components required in the smart card reader are a LED to provide visual indication of data flow activity, the passthrough connector and in some embodiment a resistor limiting the current in the LED. The present invention provides a method and device that allows USB traffic between a host computer and a USB smart card to be visualized.
A method having features of the present invention comprises transmitting and receiving USB packets comprising differential serial signals between the smart card module and the USB port, generating a correct transfer signal by the smart card module upon successful transmission and reception of a USB packet and signaling transaction activity based on the correct transfer signal. The signaling step may include connecting the correct transfer signal to an input of a counter, both positioned within the smart card module, and signaling transaction activity based on an output of the counter. The method may further include selecting an output of the counter so that the user is provided with a perceptible indication of signaling transaction activity. It may also include connecting the output of the counter to an output buffer positioned within the smart card module that drives a LED. The output buffer may comprise a current source circuit connected to a GND reference voltage. The output buffer may comprise a current source circuit connected to a VBUS supply voltage. The output buffer may comprise a switch circuit connected to a VBUS supply voltage. The output buffer may comprise a switch circuit connected to a GND reference voltage.
Another embodiment of the present invention may comprise transmitting and receiving USB packets comprising differential serial signals between the USB port and external terminals of transceivers positioned within the smart card module, connecting internal terminals of the transceivers to inputs of a serial engine positioned within the smart card module, interconnecting a correct transfer signal from an output of the serial engine to a micro-controller and a counter, both positioned within the smart card module, controlling the counter from the micro-controller, driving an input of an output buffer positioned within the smart card module from an output of the counter, and activating a device from an output of the output buffer for signaling transaction activity based on the correct transfer signal. The device being activated may be a LED, having an anode and a cathode.
The method may further include connecting the anode of the LED to a VBUS supply voltage of the smart card module, connecting the cathode of the LED to an I/O contact of the smart card module, connecting a second NMOS transistor of a current mirror circuit within the smart card module between the I/O contact and a GND reference voltage contact for providing a modulated current sink for illumination of the LED, connecting a first NMOS transistor of the current mirror circuit within the smart card module to the second NMOS transistor, and providing a modulated current to the first NMOS transistor from the output of the output buffer that reflects the USB transaction activity, causing the illumination intensity of the LED to be modulated according to the USB transaction activity. The cathode of the LED may be connected to a contact of the smart card module selected from the group consisting of C2, C3, C6 and C7.
The method may further include connecting the anode of the LED to an I/O contact of the smart card module, connecting the cathode of the LED to a GND reference voltage of the smart card module, connecting a second PMOS transistor of a current mirror circuit within the smart card module between the I/O contact and a VBUS Supply voltage contact for providing a modulated current sink for illumination of the LED, connecting a first PMOS transistor of the current mirror circuit within the smart card module to the second PMOS transistor, and providing a modulated current to the first PMOS transistor from the output of the output buffer that reflects the USB transaction activity, causing the illumination intensity of the LED to be modulated according to the USB transaction activity. The method may include the anode of the LED being connected to a contact of the smart card module selected from the group consisting of C2, C3, C6 and C7.
The method may further include connecting the cathode of the LED to a GND reference voltage of the smart card module, connecting a first terminal of a resistor to the anode of the LED, connecting a second terminal of the resistor to an I/O contact of the smart card module, connecting a PMOS transistor switch of a current switch circuit within the smart card module between the I/O contact and a VBUS supply voltage contact, and providing a modulated voltage source from the output of the output buffer that reflects the USB transaction activity to a gate terminal of the PMOS transistor switch within the smart card module, causing the illumination intensity of the LED to be modulated according to the USB transaction activity. The second terminal of the resistor may be connected to a contact of the smart card module selected from the group consisting of C2, C3, C6 and C7.
The method may further comprise connecting the anode of the LED to a VBUS supply voltage of the smart card module, connecting a first terminal of a resistor to the cathode of the LED, connecting a second terminal of the resistor to an I/O contact of the smart card module, connecting an NMOS transistor switch of a current switch circuit within the smart card module between the I/O contact and a GND reference voltage contact, and providing a modulated voltage source from the output of the output buffer that reflects the USB transaction activity to a gate terminal of the NMOS transistor switch within the smart card module, causing the illumination intensity of the LED to be modulated according to the USB transaction activity. The second terminal of the resistor may be connected to a contact of the smart card module selected from the group consisting of C2, C3, C6 and C7.
A further embodiment of the present invention is a device comprising transceivers positioned within the smart card module for transmitting and receiving USB packets comprising differential serial signals between the USB port and external terminals of transceivers, the transceivers having internal terminals connected to inputs of a serial engine positioned within the smart card module, a correct transfer signal from an output of the serial engine interconnected to a micro-controller and a counter, both positioned within the smart card module, the counter being controlled from the micro-controller, an output of the counter driving an input of an output buffer positioned within the smart card module, and a device activated from an output of the output buffer for signaling transaction activity based on the correct transfer signal. The device being activated may be a LED, having an anode and a cathode.
The device may further include the anode of the LED connected to a VBUS supply voltage of the smart card module, the cathode of the LED connected to an I/O contact of the smart card module, a second NMOS transistor of a current mirror circuit within the smart card module connected between the I/O contact and a GND reference voltage contact for providing a modulated current sink for illumination of the LED, a first NMOS transistor of the current mirror circuit within the smart card module connected to the second NMOS transistor, and a modulated current provided to the first NMOS transistor from the output of the output buffer that reflects the USB transaction activity, causing the illumination intensity of the LED to be modulated according to the USB transaction activity. The cathode of the LED may be connected to a contact of the smart card module selected from the group consisting of C2, C3, C6 and C7.
The device may further comprise the anode of the LED connected to an I/O contact of the smart card module, the cathode of the LED connected to a GND reference voltage of the smart card module, a second PMOS transistor of a current mirror circuit within the smart card module connected between the I/O contact and a VBUS supply voltage contact for providing a modulated current sink for illumination of the LED, a first PMOS transistor of the current mirror circuit within the smart card module connected to the second PMOS transistor, and a modulated current provided to the first PMOS transistor from the output of the output buffer that reflects the USB transaction activity, causing the illumination intensity of the LED to be modulated according to the USB transaction activity. The anode of the LED is connected to a contact of the smart card module selected from the group consisting of C2, C3, C6 and C7.
The device may further comprise the cathode of the LED connected to a GND reference voltage of the smart card module, a first terminal of a resistor connected to the anode of the LED, a second terminal of the resistor connected to an I/O contact of the smart card module, a PMOS transistor switch of a current switch circuit within the smart card module connected between the I/O contact and a VBUS supply voltage contact, and a modulated voltage source provided from the output of the output buffer that reflects the USB transaction activity to a gate terminal of the PMOS transistor switch within the smart card module, causing the illumination intensity of the LED to be modulated according to the USB transaction activity. The second terminal of the resistor is connected to a contact of the smart card module selected from the group consisting of C2, C3, C6 and C7.
The device may further include the anode of the LED connected to a VBUS supply voltage of the smart card module, a first terminal of a resistor connected to the cathode of the LED, a second terminal of the resistor connected to an I/O contact of the smart card module, an NMOS transistor switch of a current switch circuit within the smart card module connected between the I/O contact and a GND reference voltage contact, and a modulated voltage source provided from the output of the output buffer that reflects the USB transaction activity to a gate terminal of the NMOS transistor switch within the smart card module, causing the illumination intensity of the LED to be modulated according to the USB transaction activity. The second terminal of the resistor may be connected to a contact of the smart card module selected from the group consisting of C2, C3, C6 and C7.